1. Field of the Invention
The present invention relates to absorbent pads. More particularly, the present invention relates to absorbent pads having contoured and/or complex shapes.
2. Description of Related Art
An absorbent pad is used for a variety of purposes including food-packaging, medical absorbent, laboratory cleanup, transportation packaging and safety, and personal hygiene. One use of an absorbent pad in the food-packaging industry is for the absorption of fluids secreted from meat, poultry, seafood, and other food products.
Absorbent pads are generally square or rectangular with straight edges. The absorbent core material is often a single layer of cellulose fluff or airlaid non-woven cut into the square or rectangular shape. The absorbent core material can also have multiple layers of tissue combined and cut into the square or rectangular shape. However, certain absorbent packaging designs are best served with unique and complex absorbent structures. Therefore, there is a commercial need for absorbent pads that are of shapes other than square or rectangular to more precisely fit an array of packaging shapes and sizes.
In conventional absorbent pads, a layer of film, non-woven material, or paper is typically attached to the upper and/or lower surface of the absorbent core material by gluing essentially at least one side of the entire inner absorbent core surface and/or the outer edges using a hot-melt or cold liquid adhesive. The inner absorbent structure, or core, is cut with straight knifes into squares or rectangles, with the surrounding film, paper or nonwovens also cut with straight blades.
The absorbent core material typically has an amount of a superabsorbent polymer (SAP) in either granule or fiber format. The superabsorbent polymer expands greatly as it absorbs liquids, posing problems for absorbent pads. As the superabsorbent polymer expands, it exerts pressure on the outside layers of the pad and the seams sealing the upper and lower layers thereby creating a risk of bursting. It is important, particularly in the food-packaging industry, to keep the superabsorbent polymer inside the absorbent pad and away from the food product before and after the swelling of the superabsorbent polymer.
Another problem that arises with the high absorbent capacity of one or more superabsorbent polymers is the desiccation of food products within the packaging. Absorbent pads have been developed that use holes, slits, or microperforations in the top sheet of the absorbent pad to allow for effective fluid absorption while minimizing the drawing effect that causes the desiccation of the food product. U.S. Pat. No. 6,270,873 describes an absorbent pad with microperforations.
Often there is a need to deliver in the absorbent pad other components, such as active ingredients. These components typically perform better when allowed to remain dry, or at a minimum, not fully immersed or saturated with liquid. For example, an enzymatic oxygen scavenger, which is used to remove oxygen from the interior of food packages to provide improved shelf life and appearance, function best when dry or only damp. An absorbent pad that would allow for one or more of these components to be placed in a separate layer, portion, or zone from the absorbent core material is desirable.
There remains a commercial need for an absorbent pad that further minimizes the potential for bursting at the seams, while also providing multiple layers, portions, or zones for separating the absorbent core from other components. It would further be desirable to have an absorbent pad that has shapes other than square or rectangular.